Observations of humpback whales (position, number and presence of calf) were obtained from a commercial whale-watching vessel during January to March 1995 to 1997 along the northwestern coast of Puerto Rico. These data represent the only information available for this area over a 15-year period. Two-hundred thirty-six whales were sighted during the three years. Relative abundances (sightings/trip) were similar during 1995 and 1997, while in 1996 abundance was greater with a distinct peak during the beginning of March. For mothers with calves, sightings were most frequent within the 0-50 m and 50-100 m depth ranges, while other humpbacks were distributed throughout all depth ranges. Compared to other whales, the proportion of mothers with calf was higher in the shallowest depth range (0-50 m) for the three years. Trends in abundance and depth distributions are consistent with previous investigations, both in Puerto Rico and elsewhere. Our study extends the spatial distribution of the humpback whales off northwestern Puerto Rico showing the importance of other offshore areas away from the insular platformCollege of Arts and Sciences University of Puerto Rico, Mayagüez