Growth of juvenile orange-spotted grouper Epinephelus coioides from a coastal reef and mangrove estuary in Northwest Peninsular Malaysia were investigated using size (TL) and daily age information obtained from otolith (lapillus) daily increment analysis. Increments in the lapillus of known-age hatchery-produced fish were deposited daily (following a 12 day delay in deposition onset) after hatching. The juveniles, collected from the coastal reef at Langkawi Island (25.9-48.0 mm TL) and the Merbok mangrove estuary (90.0-232.0 mm TL), Malaysia, were estimated to be 31-53 and 85-217 days old, respectively. Back-calculation of hatching dates showed that E. coioides spawned throughout most of the year in the region, probably due to the year-round constant water temperatures (>27°C). Age and size information also indicated that the juveniles entered the mangrove estuary from the coastal area at ca. 90 mm TL (> 85 days old), growing to over 200 mm TL over a more than 4 month (maximum) period in the estuary, and disappeared by ca. 230 mm TL (maximum age 217 days old). Growth rates (mm per day) of the juveniles from the mangrove estuary hatched in each quarter were 0.84 mm in January-March, 0.90 mm in April-June, 0.77 mm in July-September and 0.90 mm in October-December, not significantly different each other, and the growth rate of aggregate juveniles from the mangrove estuary being 0.91 mm. The growth pattern of E. coioides during some 7 months after hatching (from hatching to disappearance from the mangrove estuary), estimated from the age-length relationship in both hatchery-produced and wild fish (including juveniles from the Langkawi coastal area and Merbok mangrove estuary), closely fitted the Gompertz growth fon-nula (L = 214.26.exp[-3.89.exp(-0.016T)] (r = 0.97)). It was estimated that E. coioides grew to ca. 90-100 mm TL by ca. 90 days old, the growth thereafter becoming slower.