The most general system of basic hypergeometric orthogonal polynomials are the Askey-Wilson polynomials, which are given as a basic hypergeometric series \(_ 4\Phi_ 3\). Like all orthogonal polynomials they satisfy a three-term recurrence relation \[ 2xp_ n(x)=A_ np_{n+1}(x)+B_ np_ n(x)+C_ np_{n-1}(x). \] The recurrence coefficients \(A_ n\), \(B_ n\), \(C_ n\) are rational functions of \(q^ n\), and thus it makes sense to consider polynomials \(p_ n^ \alpha(x)\) generated by \[ 2xp_ n^ \alpha(x)=A_{n+\alpha}p_{n+1}^ \alpha(x)+B_{n+\alpha}p_ n^ \alpha(x)+C_{n+ \alpha}p_{n-1}^ \alpha(x), \] where \(\alpha\) is real. These polynomials are the associated Askey-Wilson polynomials. The present paper contains a wealth of results about these polynomials and some closely related polynomials \(q_ n^ \alpha(x)\) with different initial conditions. Among these results are explicit expressions in terms of well-poised \(_ 8\Phi_ 7\) basic hypergeometric series. The change of variable \(2x=z+z^{-1}\) leads to an expression in the variable \(z\) for which the coefficients are well-poised \(_{10}\Phi_ 9\) basic hypergeometric series. This expression quickly leads to an asymptotic formula for \(x\in\mathbb{C}\backslash[-1,1]\). The orthogonality measure is obtained by using the Perron-Stieltjes inversion formula but also by using a result of Nevai about the relation between the asymptotic behaviour of orthogonal polynomials and the weight function. Other results include the positivity of the linearization coefficients. This is a quite technical paper containing various results on basic hypergeometric series, such as contiguous relations and the location of zeros of well-poised basic hypergeometric series. But all these technical results do lead to beautiful results for the associated Askey-Wilson polynomials.