The long-acting analogue of luteinizing hormone releasing hormone, D-Trp6-Pro9-NEt-LHRH (LHRHa), is effective in the short-term treatment of central precocious puberty. We report the results of two to four years of LHRHa therapy in 27 children with this disorder. Secondary sex characteristics regressed in most patients. Sex steroid levels and basal and LHRH-stimulated gonadotropin levels remained suppressed compared with pretreatment values. Linear growth rates decreased from 11.0±0.8 (SEM) cm/yr before treatment to 5.7 ±0.4 cm/yr at two years of treatment and 3.7±0.7 cm/yr at four years of treatment. Predicted heights by the Bayley-Pinneau method increased from 156.4 ±2.0 cm before treatment to 162.3 ±2.3 cm at two years and 163.4 ±2.4 cm at three years. Five patients treated for four years had a mean increase in predicted height of 5.5 cm. To date no adverse effects have been observed. However, the ultimate safety of this analogue is not known. We conclude that LHRHa appears to be an effective long-term therapy for central precocious puberty.