Some new inequalities of Ostrowski-Grüss type are derived. They are applied to the error analysis for some Gaussian and Gaussian-like quadrature formulas. 1. Introduction. In this paper we derive some new inequalities of Ostrowski-Grüss type. They are applied to the error analysis for some Gaussian and Gaussian-like quadrature formulas. We consider Gauss-Legendre, Chebyshev, Radau and Lobatto quadratures. A similar error analysis for rules of Newton-Cotes type can be found in the literature. In particular, the mid-point, trapezoid and Simpson rules have been investigated recently ([1], [2], [4], [8], [11]) with a view to obtaining bounds on the quadrature rule in terms of a variety of norms involving, at most, the first derivative. The present work brings results for the above mentioned Gaussian and Gaussian-like quadrature rules giving explicit error bounds. We use Peano type kernels and an approach via inequalities. The error bounds are expressed in terms of first derivatives. The general approach used in the past required the assumption of bounded derivatives of degree higher than one. Our error bounds are in general (but not always) better than the Peano bounds. We also consider composite quadrature rules. Our analysis allows the determination of a partition that would assure a prescribed error tolerance. In Section 2 we establish some inequalities of Ostrowski-Grüss type. Such inequalities are considered in [2], [4], [8] and [11]. In Sections 3-6 we apply these inequalities to obtain explicit error bounds for the above mentioned quadrature rules. In Section 7 we give a general procedure for forming