  We present the perturbative renormalization group functions of
$O(n)$-symmetric $\phi^4$ theory in $4-2\varepsilon$ dimensions to the sixth
loop order in the minimal subtraction scheme. In addition, we estimate diagrams
without subdivergences up to 11 loops and compare these results with the
asymptotic behaviour of the beta function. Furthermore, we perform a
resummation to obtain estimates for critical exponents in three and two
dimensions.
