On April 7, 1986, Librado Vargas was recruited by the petitioner, GRF Shipping Agency, Inc., to work as a third engineer, with a monthly salary of $615, on board the M/V 'Barbara Morgan,' a vessel of Chaldeos Freighters Ltd.

On February 14, 1987, while the ship was on its way to Cuiota, Morocco, Vargas felt severe pain in the region of his previous hernia operation, apparently caused by excessive physical exertion on his part while calibrating the main engine injection valve of the ship, a task which ordinarily would have required at least two or more persons to perform.  He was given first aid treatment and when the ship arrived in Tunisia, he was examined by a Tunisian doctor, Dr. Rekik Abbdellatif, who found that he was suffering from hernia, and recommended his immediate repatriation for further treatment.  However, the ship captain advised him to wait for the shipowner or his representative.

On February 26, 1987, Benjamin Sabat, the recruiter's representative, arrived in Tunisia.  He was notified of Vargas' illness.  On March 2, 1987, Sabat brought Vargas to the same Tunisian doctor who had earlier examined him.  The doctor affirmed his previous diagnosis that Vargas was suffering from hernia and recommended his immediate repatriation to the Philippines.  He issued another medical certificate to that effect.

Notwithstanding the doctor's advice, Sabat wanted Vargas to await the ship's arrival in Greece, which would take about two months of navigation, as repatriation was allegedly not allowed by the laws of Tunisia. Vargas sought the help of the ship's agent who brought the matter to the attention of the Port Authority in Spax, Tunisia.  He was thereafter allowed by Sabat to be repatriated and he was advised to draw his salary for February, 1987, from the petitioner upon his arrival in Manila.

Upon his arrival in the Philippines, Vargas was brought for treatment to the company's doctor, a certain Dr. Gavino.  He was treated at the FEU Hospital until he recovered from his illness.  Dr. Gavino opined that Vargas suffered from Spermatic Cord Infection, a disease not subject to repatriation.  As a result, the petitioner deducted from Vargas' February salary the sum of P9,704.90 for the medical expenses defrayed by the petitioner, and P5,300.00 from his salaries for June and August, 1986.

On April 24, 1987, Vargas filed a complaint for non-payment of wages, illegal deductions, and unpaid medical benefits.

On June 17, 1988, the POEA rendered a decision allowing his claims.  The dispositive portion of the decision reads:

"WHEREFORE, foregoing premises considered, judgment is hereby rendered ordering as follows:

"Payment by respondent GRF Shipping Agency unto the complainant the following:

"1.  P9,704.90 representing medical expenses deducted from his allotment for February, 1987;

"2.  P5,300.00 representing the amount deducted from his salaries for June and August 1986;

"3.  US$615.00 - his sickness wages from 1 March to 2 April 1987; and

"4.  P3,000.00 as and for attorney's fees, to be tendered thru this office within ten (10) days from receipt hereof." (pp. 31-32, Rollo.)

The petitioner appealed to the National Labor Relations Commission.  On September 29, 1990, the NLRC dismissed the appeal, and affirmed in toto the POEA's decision.  Hence, this petition for certiorari.

The issue raised by the petition is whether or not the NLRC gravely abused its discretion in finding that, as certified by the Tunisian doctor, Vargas' ailment was hernia (which is a cause for repatriation of the employee) and not spermatic cord infection, as found by the petitioner's Manila doctor, which is not a ground for repatriation.  This is a factual question which is for the public respondents, as triers of fact, to determine.  "Well settled is the rule that factual findings of quasi-judicial agencies like the National Labor Relations Commission, which have acquired expertise because their jurisdiction is confined to specific matters, are generally accorded not only respect but at times even finality if such findings are supported by substantial evidence." (Baby Bus, Inc. vs. Minister of Labor, 158 SCRA 221.) The NLRC correctly observed that the medical certificate issued by the petitioner's own physician was self-serving evidence.  As such, its probative value is inferior compared with the medical certificate issued in Tunisia by an impartial foreign doctor in the presence of petitioner's own representative who did not question its veracity and authenticity at the time.

WHEREFORE, the petition for certiorari is dismissed for lack of merit.

SO ORDERED.

Narvasa, (Chairman), Cruz, Gancayco, and Medialdea, JJ., concur.