PHP-1 can be divided into 2 groups, with either diminished(A)or normal (B) G stimulatory regulatory protein activity(Gs) of the hormone receptor-adenylate cyclase system. In 14 PHP-1 patients (pts), aged 9 mos to 22 yrs we measured erythrocyte Gs protein activity and performed detailed endocrine evaluation for evidence of multiple hormonal dysfunction, as previously shown in PHP-1A adults (Am J Med 1983:74,545).Results: 6 pts had PHP-1A (↓Gs) and all had classical clinical features (Albright's Hered. Osteodyst.-AHO). In this group hypothyroidism was diagnosed in 2 neonates by thyroid screening (↑TSH) and 2 others had low/low N T4 & ↑TSH but neg. thyroid antibodies. All received L-thyroxine. Two girls had an exaggerated LH response to LHRH (Δmax 74 & 93.4 U/L),the first with delayed puberty and delayed menarche (21 yrs) Three pts, 2 with primary enuresis, had elevated AVP/plasma Osm ratios after water deprivation. Eight pts had PHP-1B, and only 1 had clinical features of AHO. Of 6 pts >11 yrs, 4 males had increased LH reserve (ΔLH 54, 59, 34.5, 85 U/L), but normal pubertal development. 4 pts had elevated AVP/plasma Osm ratio, 1 with primary enuresis.Conclusion:(1) AHO is a good clinical marker for PHP-1A in children (2) in PHP-1A, multiple hormone resistance of variable severity is common, with hypothyroidism, pubertal delay and nocturnal enuresis as presenting clinical features (3) In PHP-1B, evidence of mild hormonal resistance is occasionally present, despite normal erythrocyte Gs protein activity.