This paper provides an improved result over that in Liu and Zhang [2003, New approaches to H-infinity controller designs based on fuzzy observers for T-S fuzzy systems via LMI. Automatica, 39, 1571-1582] for the problem of observer-based H-infinity control for nonlinear systems in Takagi-Sugeno (T-S) fuzzy model. It contributes in three aspects: (i) The present result is less conservative than that in Liu and Zhang [2003, New approaches to H-infinity controller designs based on fuzzy observers for T-S fuzzy systems via LMI. Automatica, 39, 1571-1582]; (ii) The present strict LMI method is a single step approach which overcomes the drawback of a two-step approach in Liu and Zhang [2003, New approaches to H-infinity controller designs based on fuzzy observers for T-S fuzzy systems via LMI. Automatica, 39, 1571-1582]; (iii) The matrix dimensions are largely reduced compared with the corresponding ones in Liu and Zhang [2003, New approaches to H-infinity controller designs based on fuzzy observers for T-S fuzzy systems via LMI. Autoinatica, 39, 1571-1582]. (c) 2005 Elsevier Ltd. All rights reserved.